Real-time navigation by fluorescence-based enhanced reality for precise estimation of future anastomotic site in digestive surgery

Background: Fluorescence-based enhanced reality (FLER) is a technique to evaluate intestinal perfusion based on the elaboration of the Indocyanine Green fluorescence signal. The aim of the study was to assess FLER's performances in evaluating perfusion in an animal model of long-lasting intestinal ischemia. Materials and methods: An ischemic segment was created in 18 small bowel loops in 6 pigs. After 2h (n=6), 4h (n=6), and 6h (n=6), loops were evaluated clinically and by FLER to delineate five regions of interest (ROIs): ischemic zone (ROI 1), presumed viable margins (ROI 2a-2b), and vascularized areas (3a-3b). Capillary lactates were measured to compare clinical vs. FLER assessment. Basal (V 0 ) and maximal (V max) mitochondrial respiration rates were determined according to FLER. Results: Lactates (mmol/L) at clinically identified resection lines were significantly higher when compared to those identified by FLER (2.43±0.95 vs. 1.55±0.33 p=0.02) after 4h of ischemia. Lactates at 2h at ROI 1 were 5.45±2.44 vs. 1.9±0.6 (2a-2b; p<0.0001) vs. 1.2±0.3 (3a-3b; p<0.0001). At 4h, lactates were 4.36±1.32 (ROI 1) vs. 1.83±0.81 (2a-2b; p<0.0001) vs. 1.35±0.67 (3a-3b; p<0.0001). At 6h, lactates were 4.16±2.55 vs. 1.8±1.2 vs. 1.45±0.83 at ROI 1 vs. 2a--2b (p=0.013) vs. 3a-3b (p=0.0035). Mean V 0 and V max (pmolO2/second/mg of tissue) were significantly impaired after 4 and 6h at ROI 1 (V 0 4h =34.83±10.39; V max 4h =76.6±29.09; V 0 6h =44.1±12.37 and V max 6h =116.1±40.1) when compared to 2a--2b (V 0 4h =67.1±17.47 p=0.00039; V max 4h =146.8±55.47 p=0.0054; V 0 6h =63.9±28.99 p=0.03; V max 6h =167.2±56.96 p=0.01). V 0 and V max were significantly higher at 3a-3b. Conclusions: FLER may identify the future anastomotic site even after repetitive assessments and long-standing bowel ischemia

Probe-based confocal laser endomicroscopy and fluorescence-based enhanced reality for real-time assessment of intestinal microcirculation in a porcine model of sigmoid ischemia

Background and aim: Surgeons currently rely on visual clues to estimate the presence of sufficient vascularity for safe anastomosis. We aimed to assess the accuracy of endoluminal confocal laser endomicroscopy (CLE) and laparoscopic fluorescence-based enhanced reality (FLER), using near-infrared imaging and fluorescence from injected Indocyanine Green, to identify the transition from ischemic to vascular areas in a porcine model of mesenteric ischemia. Methods: Six pigs underwent 1-h sigmoid segmental ischemia. The ischemic area was evaluated by clinical assessment and FLER to determine presumed viable margins. For each sigmoid colon, 5 regions of interest (ROIs) were identified: ischemic (ROI 1), presumed viable margins ROI 2a (distal) and 2b (proximal), and vascular areas 3a (distal) and 3b (proximal). After injection of fluorescein, CLE scanning of the mucosa from the ischemic area toward viable margins was performed. Capillary blood samples were obtained by puncturing the serosa at the ROIs, and capillary lactates were measured with the EDGE® analyzer. Results: Capillary lactates were significantly higher at ROI 1 (4.91mmol/L) when compared to resection margins (2.8mmol/L; mean difference: 2.11; p<0.05) identified by FLER. There was no significant difference in lactates between ROI1 and resection margins identified by clinical evaluation. In 50% of cases, ROI 2aCLINIC-2bCLINIC were considered to match (<1cm distance) with ROI 2aFLER-2bFLER. Confocal analysis revealed specific clues to identify the transition from ischemic to viable areas corresponding to those assessed by FLER in 11/12 cases versus 7/12 for those identified by clinical evaluation. Conclusions: In this experimental model, FLER and CLE were more accurate than clinical evaluation to delineate bowel vascularization